Electric motor and turntable drive



July 11, 1961 MEIJER 2,992,343

ELECTRIC MOTOR AND TURNTABLE DRIVE Filed May 6, 1957 INVENTOR BAREND MARTINUS MEIJER AGENT United States Patent 2,992,343 ELECTRIC MOTOR AND TURNTABLE DRIVE Barend Martinus Meijer, Eindhoven, Netherlands, assignor to North American Philips Company, Inc., New

York, N.Y., a corporation of Delaware Filed May 6, 1957, Ser. No. 657,276 Claims priority, application Netherlands June 5, 1956 2 Claims. (Cl. 310-76) This invention relates to devices which are known from US. Patent No. 2,626,528 and intended for driving sound record carriers both for recording and reproducing oscillations, by means of an electric motor, preferably a synchronous motor, and an intermediate wheel which is mechanically disengaged from the driving and the driven wheel through an electro-magnetic relay in its de-energized condition. This known device comprises a separate relay for said purpose.

The device referred to has the advantage that as long as the motor is energized, the relay is also energized, the

intermediate wheel, which may comprise a resilient rim, establishing the coupling between the driving and the driven wheel, while disconnection of the motor involves de-energization of the relay, hence decoupling. In this case, the resilient rim of the intermediate wheel stands clear from both wheels, so that deformation of this rim and consequently speed variations of the record carrier are avoided.

According to the invention a simpler and more economical device is obtained by combining the relay with the motor to form an assembly so that also the magnetic circuit of the relay energized by the stator winding of the motor, and the magnetic circuit of the relay comprises at least one short-circuited turn. This last-mentioned step prevents the alternating voltage energized relay from tending to chatter due to the zero-passages of the voltage.

The magnetic circuit of the relay preferably comprises two pairs of short-circuited windings which produce a phase-shift of 30 to 40 and 70 to 80 respectively of the flux through the short-circuited windings, hence the relay is less sensitive to the alternating flux of the main field.

In order that the invention may be readily carried into effect, an example will now be described in detail with reference to the accompanying single figure of a schematic drawing, in which The motor comprises a winding 1, a stator 2 and a rotor 3 to the shaft of which a roller 4 is secured. The winding 1 also comprises a magnetic circuit 5 of a relay, whose armature 7 pivoted on the spindle 6 comprises two pairs of short-circuited turns 8 and 9. In the deenergized condition of the relay, the armature 7 is opened by a drawspring 10. When the relay is energized by the coil 1 the armature is attracted and an intermediate wheel 11 is made to engage the roller 4 and the inner edge 15 of the turntable of a record player, which is thus driven, through articulated levers 12, 13 having a center of rotation 14 in the position shown in broken lines.

The end faces 16 of the armature and the faces 17 should be accurately surface-ground. In order to prevent sticking of the armature, it is preferably provided with an air-gap 18 of 0.1 to 0.5 mm.

Of course, the two circuits 2 and 5 may be made to form an assembly. This drive is also suited for recording and reproducing magnetic records.

What I claim is:

1. A turn-able motor drive comprising an electro-magnetic relay, a drive wheel operatively connected to the motor, a movable intermediate wheel which in operative position engages both the drive wheel and the turntable, a linkage connecting the armature of the relay and said intermediate wheel, said linkage having at least two coupled arms, and means mounting one of said arms for pivotal movement whereby said intermediate wheel is movable into its operative and inoperative positions, said electromagnetic relay controlling the movement of said intermediate wheel through said linkage, the magnetic circuit of the relay being energized by the stator winding of the motor.

2. A turntable motor drive comprising an electro-magnetic relay, a drive wheel operatively connected to the motor, a movable intermediate wheel which in operative position engages both the drive wheel and the turntable, a linkage connecting the armature of the relay and said intermediate wheel, said linkage having arms coupled together for articulation, one of said arms having said intermediate wheel mounted at the free end thereof, and means mounting said one arm for pivotal movement whereby said intermediate wheel is movable into its operative and inoperative positions, said electro-magnetic relay controlling the movement of said intermediate wheel through said linkage, the magnetic circuit of the relay being energized by the stator winding of the motor, said relay having at least one short-circuited turn.

References Cited in the file of this patent UNITED STATES PATENTS 521,138 Crowdus June 5, 1894 1,734,941 Cowles Nov. 5, 1929 1,822,679 Stewart et a1. Sept. 8, 1931 1,979,127 Warrick Oct. 30, 1934 2,489,098 Marble Nov. 22, 1949 2,732,724 Tateisni Jan. 31, 1956 FOREIGN PATENTS 392,449 Great Britain May 18, 1933 

